Applicant previously proposed a topsheet for use on the skin facing side of an absorbent article (see Patent Document 1). The topsheet is composed of an upper layer and a lower layer both formed of a substantially inextensible sheet which are partially bonded to each other at a number of joints. The upper layer project outward toward the skin of a wearer in other than the areas of the joints to form a number of projections. The topsheet exhibits excellent leak-proof against liquid, especially a highly viscous liquid, such as loose stool or menstrual blood, and high capability of hiding absorbed liquid.
Nevertheless, the demand has ever been increasing for the improvement of performance of absorbent articles.
Patent Document 1 US 200410140047A1
The present invention provides a composite sheet comprising a substantially flat lower fibrous sheet and an upper fibrous sheet bonded to the lower fibrous sheet, the upper fibrous sheet being three-dimensionally textured with a number of projections and a number of depression each of which is located between every adjacent two of the projections,
the projections and the depressions alternating in a first direction of the composite sheet and in a second direction perpendicular to the first direction,
the projections each having a pair of opposing first walls parallel to the first direction, a pair of opposing second walls parallel to the second direction, and a top plane connected to the upper edge of each first wall and the upper edge of each second wall, and
the basis weight of each first wall being different from that of each second wall.
The present invention also provides a process of producing the composite sheet, the process comprising the steps of:
providing a first roller having projections and depressions on the peripheral surface thereof and rotating in one direction and a second roller having projections and depressions mating with the depressions and the projections of the first roller on the peripheral surface thereof and rotating in the opposite direction to at substantially the same rotating speed as the first roller,
feeding an upper fibrous sheet into an engaged portion between the rollers at a speed higher than a peripheral speed of the rollers,
three-dimensionally texturing the upper fibrous sheet by the engagement of the rollers while holding the upper fibrous sheet to the periphery of the first roller by suction,
superposing a lower fibrous sheet on the textured upper fibrous sheet while holding the upper fibrous sheet to the periphery of the first roller by suction, and
bonding the two fibrous sheets at their parts located on the top faces of the projections of the first roller.